The advent of US circuit breaker manufacturers into the world market requires a larger number of poles when such circuit breakers are used in industrial applications.
Typical US electrical distribution systems provide 3 pole service compared to 4 pole service in some European and Asian countries where there is a need to switch the neutral conductor. Since the additional poles often require expensive molding operations to provide increased space, the provision of 4 or more pole industrial rated circuit breakers over a wide range of circuit breaker ampere ratings could increase the cost of such breakers to manufacture and sell.
An early approach to providing increased circuit breaker poles to existing 3 pole circuit breakers is found in U.S. Pat. No. 4,644,308 entitled "Variable Composition Switching Device Realizable by the Assembly of Modular Elements".
Another way to provide increased circuit breaker poles to existing 3 pole circuit breaker designs is found in U.S. Pat. No. 5,298,874 entitled "Range of Molded Case Low Voltage Circuit Breakers".
A further approach is described within U.S. Pat. No. 5,479,143 entitled "Multipole Circuit Breaker with Modular Assembly" wherein the individual circuit breaker pole components are in a modular configuration.
A state-of-the-art circuit breaker employing modular pole units for low voltage circuit breakers is found in U.S. Pat. No. 5,607,047 entitled "Circuit Breaker Housing".
FIG. 1 shows a three pole industrial-rated molded case circuit breaker comprising three separate poles for connecting with an exterior electric distribution circuit having three phase A-C. This industrial rated circuit breaker is disclosed in U.S. Pat. No. 5,361,052 entitled "Industrial-Rated Circuit Breaker Having Universal Application". The three pole industrial-rated molded case circuit breaker 100 comprises a plastic base 111 to which a plastic cover 112 is attached. The cover includes a handle aperture 113 through which an operating handle 114 extends. The operating handle interacts with the circuit breaker operating mechanism that controls the ON/OFF status of the circuit breaker contacts (not shown) in the manner described within U.S. Pat. No. 5,361,052. Each of the three separate poles of the circuit breaker connect with a separate phase of the exterior electric distribution circuit via load straps 109A-109C. Corresponding line straps (not shown) that connect with associated electrical equipment are located at the opposite end of the circuit breaker case. When more than three poles are required, it is common to mold larger circuit breaker having four of more poles integrally-formed therein.
It would be economically advantageous to have a single circuit breaker modular design for high ampere-rated circuit breakers without requiring separated molded plastic enclosures for each multipole circuit breakers over a wide range of ampere ratings. The modular approach makes the best use of a base unit supporting individual modules for low equipment cost to produce providing a diversity of products in 3, 4 or more pole combinations with a few number of unique components.
One purpose of the invention is to provided a wide range of multipole circuit breakers over a wide range of ampere ratings based on a common platform that accepts any number of modular pole units to accommodate up to 4 or more pole circuit breaker applications.